In HIV-1 infected individuals, CD4-bearing T cells become functionally deficient early in the course of infection, and are numerically depleted in advanced stages of the disease. Also, it was found that the ratio of TH1 to TH2 undergoes reversion in many patients who show signs of deterioration. In designing new subunit vaccines for immunization of high risk individuals or for boosting seropositive individuals, four goals were set: (a) to identify HIV-1 subunits which will generate widely cross neutralizing antibodies, (b) to identify a carrier which will increase the immunogenicity of the HIV-1 subunits, (c) to identify a carrier which will recall anti-HIV B memory cells in patients with pre-existing immune deficiency, and (d) to identify a carrier which would augment the TH1/TH2 ratio of infected individuals. The gram negative Brucella abortus (Ba), and LPS derived from its cell wall (Ba-LPS), were found to fulfill the last three goals. Inactivated HIV-1 linked to Ba, was found to be more immunogenic than unconjugated HIV-1, not only in normal mice, but also in CD4-depleted mice. The antibodies generated were predominantly of the IgG2B/2A, and they blocked efficiently HIV-1 env-mediated syncytia formation. In recent studies it was found that the Ba or its LPS are much less toxic to animals than E. Coli derived LPS. More importantly, it was found that Ba and Ba-LPS activate directly purified human CD4-positive TH1 cells, and to a lesser degree, CD8-positive cells, as judged by induction of the lymphokines IL2 and IFN-gamma. We are currently employing sensitive PCR techniques to measure lymphokine production by adult and neonatal T cells activated by Ba. We also studying what DNA- binding proteins are induced following Ba or Ba-LPS activation of human T cells. In addition, several gp120-subunits are being tested for their ability to generate cross neutralizing antibodies after conjugation to Ba and Ba-LPS.